The inadequate treatment of municipal solid waste which is being put in landfills and the increasing addition of nondegradable materials, including plastics, to municipal solid waste streams are combining to drastically reduce the number of landfills available and to increase the costs of municipal solid waste disposal. While recycling of reusable components of the waste stream is desirable in many instances, the costs of recycling and the infrastructure required to recycle materials is sometimes prohibitive. In addition, there are some products which do not easily fit into the framework of recycling. The composting of nonrecyclable solid waste is a recognized and growing method to reduce solid waste volume for landfilling and/or making a useful product from the waste to improve the fertility of fields and gardens. One of the limitations to marketing such compost is the visible contamination by undegraded plastic, such as film or fiber fragments.
It is desired to provide components which are useful in disposable products and which are degraded into less contaminating forms under the conditions typically existing in waste composting processes. These conditions may involve temperatures no higher than 70° C., and averaging in the 55-60° C. range, humid conditions as high as 100 percent relative humidity, and exposure times which range from weeks to months. It is further desirable to provide disposable components which will not only degrade aerobically/anaerobically in composting, but will continue to degrade in the soil or landfill. As long as water is present, they will continue to break down into low molecular weight fragments which can be ultimately biodegraded by microorganisms completely into biogas, biomass, and liquid leachate, as for natural organics like wood.
Polyesters have been considered for biodegradable articles and enduses in the past. These biodegradable polyesters can be described as belonging to three general classes: aliphatic polyesters; aliphatic-aromatic polyesters; and sulfonated aliphatic-aromatic polyesters.
Aliphatic polyesters include polyesters derived solely from aliphatic dicarboxylic acids, such as poly(ethylene succinate), poly(1,4-butylene adipate), and the like, as well as poly(hydroxyalkanates), such as polyhydroxybutyrate, polylactide, polycaprolactone, polyglycolide, and the like. U.S. Pat. No. 3,932,319 to Clendinning et al. teaches the use of biodegradable aliphatic polyesters, such as poly(ethylene adipate), in biodegradable blends. U.S. Pat. No. 4,076,798 to Casey et al. teaches biodegradable resins derived from diglycollic acid and an unhindered glycol. U.S. Pat. No. 5,256,711 to Tokiwa et al. discloses a biodegradable plastic material which is a mixture of gelatinized starch and biodegradable, aliphatic polyesters. U.S. Pat. Nos. 5,292,783, 5,559,171, 5,580,911, and 5,599,858 to Buchanan et al. teach biodegradable blends of certain cellulose derivatives with aliphatic polyesters, aliphatic-aromatic polyesters, and combinations thereof. U.S. Pat. No. 5,300,572 to Tajima et al. discloses a process to produce high molecular weight, biodegradable aliphatic polyesters. U.S. Pat. No. 5,324,794 to Taka et al. discloses biodegradable films, U.S. Pat. No. 5,349,028 to Takahashi discloses biodegradable fiber, and U.S. Pat. No. 5,530,058 to Imaizumi discloses biodegradable filled compositions from the above mentioned aliphatic polyester. U.S. Pat. Nos. 5,391,700 and 5,616,681 to Itoh et al. teach a process to produce an aliphatic polyester. U.S. Pat. Nos. 5,653,930 and 5,780,368 to Noda et al. disclose processes to produce biodegradable fibrils from polyhydroxyalkanoates. U.S. Pat. No. 5,714,569 to Imaizumi et al. discloses branched aliphatic polyester compositions. U.S. Pat. No. 5,786,408 to Kuroda et al. teaches biodegradable compositions which include a polylactone resin, an aliphatic polyester resin, and an aliphatic polyisocyanate compound. U.S. Pat. No. 6,083,621 to Sugimoto teaches biodegradable aliphatic polyester compositions which are filled with a dried powder of fine fibers of a coconut mesocarp.
Aliphatic-aromatic polyesters include polyesters derived from a mixture of aliphatic dicarboxylic acids and aromatic dicarboxylic acids. U.S. Pat. No. 3,948,859 to Sublett et al. teaches hot melt adhesive compositions which comprise a copolyester derived from 75-95 mole percent terephthalic acid, 5-25 mole percent adipic acid, 55-85 mole percent of 1,6-hexanediol, and about 15-45 mole percent ethylene glycol. U.S. Pat. No. 4,166,895 to Buxbaum et al. discloses copolyesters of 1,4-butanediol with 8-12 mole percent of a saturated dicarboxylic acid having 6 to 36 carbon atoms, 26-32 mole percent of terephthalic acid, and 7.5 to 12 mole percent isophthalic acid. U.S. Pat. No. 4,328,059 to Horlbeck et al. teaches a process to produce polyesters by condensing 40-85 mole percent of terephthalic acid, optionally half of which component can be replaced with another dicarboxylic acid, 60-15 mole percent adipic acid, with an alkanediol of 2-6 carbon atoms in its carbon chain. U.S. Pat. No. 4,419,507 to Sublett teaches copolyesters derived from 100 mole percent of a dibasic acid component comprising 40-100 mole percent terephthalic acid and 0-60 mole percent of a second dicarboxylic acid containing 3-12 carbon atoms and 100 mole percent of glycol component comprising 40-100 mole percent 1,4-butanediol, and 0-60 mole percent di(ethylene glycol). Representative of the copolyesters disclosed in this patent is the polyester prepared from 50 mole percent glutaric acid and 50 mole percent of terephthalic acid with 1,4-butanediol.
U.S. Pat. No. 5,446,079 to Buchanan et al. teaches biodegradable aliphatic-aromatic copolyesters which comprise 40-60 mole percent of aliphatic dicarboxylic acids selected from the group consisting of glutaric acid and adipic acid, and 60-40 mole percent of aromatic dicarboxylic acids with 8 to 12 carbon atoms with diols selected from the group consisting of 1,4-butanediol and 1,6-hexanediol. U.S. Pat. No. 5,594,076 to Gordon et al. discloses hydrodegradable copolyester consisting essentially of a substantially non-degradable aromatic polyester and a hydrodegradable oxalate subunit. U.S. Pat. Nos. 5,661,193 and 6,020,393 to Khemani teach foamable, biodegradable aliphatic-aromatic copolyesters which include a branching agent. U.S. Pat. No. 6,096,809 to Lorcks et al. teaches biodegradable compositions consisting of blends of thermoplastic starch with, for example, aliphatic-aromatic polyesters. U.S. Pat. No. 6,342,304 to Buchanan et al. discloses uniaxially or biaxially oriented films prepared from aliphatic-aromatic copolyesters.
Polyetheresters include polyesters which incorporate poly(alkylene ether) glycols, such as poly(ethylene glycol), poly(trimethylene ether glycol), poly(tetramethylene ether)glycol, and the like. Polyetherester compositions are known within the art. See, for example, U.S. Pat. Nos. 2,744,087, 3,243,413, 3,558,557, 3,880,976, 4,256,860, 4,349,469, 4,355,155, 4,840,984, 4,906,729, 4,937,314, 4,968,778, 4,970,275, 4,985,536, 5,128,185, 5,331,066, and 6,046,302.
Aliphatic-aromatic polyetheresters include polyesters derived from a mixture of aliphatic dicarboxylic acids and aromatic dicarboxylic acids which incorporate poly(alkylene ether) glycols. Aliphatic aromatic polyetheresters are generally known within the art. See, for example, U.S. Pat. Nos. 3,023,192, 3,261,812, 3,663,653, 3,701,755, 3,763,109, 3,766,146, 3,775,373, 3,775,374, 3,775,375, 3,784,520, 3,801,547, 4,003,882, 4,003,883, 4,136,715, 4,250,280, 4,262,114, 4,467,595, 4,670,498, 4,687,835, 4,929,714, 5,882,780, and 5,958,567.
U.S. Pat. No. 3,103,914 to Willard exemplifies aliphatic aromatic polyetheresters, for example, containing 85 mole percent ethylene glycol, 15 mole percent poly(tetramethylene oxide)glycol with an average molecular weight of 1005, 85 mole percent terephthalic acid, and 15 mole percent sebacic acid (Example 1), and 90 mole percent ethylene glycol, 10 mole percent poly(tetramethylene oxide)glycol with an average molecular weight of 1005, 70 mole percent terephthalic acid, and 30 mole percent sebacic acid.
U.S. Pat. No. 3,651,014 to Witsiepe exemplifies aliphatic aromatic polyetherester compositions containing 82.4 mole percent 1,4-butanediol, 17.6 mole percent poly(tetramethylene oxide)glycol, 80 mole percent terephthalic acid, and 20 mole percent adipic acid. (See, column 13, line 1, Example 5.)
U.S. Pat. No. 3,981,833 to Lark exemplifies aliphatic aromatic polyetherester compositions consisting of, for example, 44.4 mole percent polyethylene glycol with an average molecular weight of 600, 44.4 mole percent neopentyl glycol, 11.1 mole percent 1,1,1-trimethylolpropane triol, 83 mole percent isophthalic acid, and 17 mole percent adipic acid. (See, Example 1.)
U.S. Pat. No. 4,156,774 to Buxbaum et al. exemplifies aliphatic aromatic polyetherester compositions which contain, for example, 55 mole percent ethylene glycol, 40 mole percent diethylene glycol, 5 mole percent poly(tetramethylene oxide) glycol, 90 mole percent terephthalic acid, and 10 mole percent azelaic acid. (See, Example 2.)
U.S. Pat. No. 4,328,278 to Subleft exemplifies the preparation of a resin composed of 70 mole percent 1,6-hexanediol, 30 mole percent diethylene glycol, 90 mole percent terephthalic acid, and 10 mole percent glutaric acid. U.S. Pat. No. 4,390,687 to Tung exemplifies aliphatic aromatic polyetherester compositions consisting of: (i) 88.7 mole percent 1,4-butanediol, 11.3 mole percent of poly(tetramethylene oxide)glycol having an average molecular weight of 1000, 86.8 mole percent terephthalic acid, and 13.2 mole percent dimer acid (Example 3); (ii) 90.1 mole percent 1,4-butanediol, 9.9 mole percent of poly(tetramethylene oxide)glycol having an average molecular weight of 1000, 95.4 mole percent terephthalic acid, and 4.6 mole percent dimer acid (Example 4); and (iii) 98 mole percent 1,4-butanediol, 2 mole percent of poly(tetramethylene oxide)glycol having an average molecular weight of 1000, 99.5 mole percent terephthalic acid, and 0.5 mole percent dimer acid (Example 7). U.S. Pat. Nos. 4,419,507 to Sublett, 4,576,997 to Trotter et al., and 4,966,959 to Cox et al. exemplify aliphatic-aromatic polyetheresters which incorporate diethylene glycol.
U.S. Pat. No. 4,328,333 to Barbee et al. exemplifies aliphatic aromatic polyetherester compositions which are comprised of: (i) 96.3 mole percent 1,4-butanediol, 3.7 mole percent of a polypropylene ether glycol, 69.4 mole percent terephthalic acid, 30 mole percent adipic acid, and 0.6 mole percent trimellitic acid (Example 6); and (ii) 96.3 mole percent 1,4-butanediol, 3.7 mole percent of a polypropylene ether glycol, 69.4 mole percent terephthalic acid, 30 mole percent 1,12-dodecanedioc acid, and 0.6 mole percent trimellitic acid (Example 7).
U.S. Pat. No. 4,598,142 to Hilbert et al. exemplifies aliphatic aromatic polyetheresters which contain, for example, 55 mole percent 1,4-butanediol, 45 mole percent diethylene glycol, 70 mole percent terephthalic acid, and 30 mole percent glutaric acid (Example 2), which was reported to have a crystalline melting temperature of 108.6° C.
U.S. Pat. No. 6,255,443 to Kinkelin et al. exemplifies aliphatic aromatic polyetherester compositions which contain: (i) 48 mole percent 1,4-butanediol, 46 mole percent 1,6-hexanediol, 6 mole percent polyethylene glycol with an average molecular weight of 600, 70 mole percent terephthalic acid and 30 mole percent adipic acid, reported to have a melting point of 78° C. (Example 1); (ii) 48 mole percent 1,4-butanediol, 46 mole percent 1,6-hexanediol, 6 mole percent polyethylene glycol with an average molecular weight of 600, 80 mole percent terephthalic acid, and 20 mole percent adipic acid, reported to have a melting point of 89° C. (Example 2); and (iii) 44 mole percent 1,4-butanediol, 50 mole percent 1,6-hexanediol, 6 mole percent polyethylene glycol with an average molecular weight of 600, 70 mole percent terephthalic acid, and 30 mole percent adipic acid, reported to have a melting point of 79° C. (Example 3).
U.S. Pat. Nos. 5,936,045, 6,046,248, 6,258,924, and 6,297,347 to Warzelhan et al. exemplify aliphatic aromatic polyetherester compositions. For example, U.S. Pat. No. 6,258,924 to Warzelhan et al. exemplifies aliphatic aromatic polyetherester compositions which contain: (i) 80 mole percent 1,4-butanediol, 20 mole percent polyethylene glycol with an average molecular weight of 600, 70 mole percent terephthalic acid, and 30 mole percent adipic acid, reported to have a melting point of 127.5° C. (Example 2); and (ii) 75 mole percent 1,4-butanediol, 25 mole percent polyethylene glycol with an average molecular weight of 600, 69.8 mole percent terephthalic acid, and 30.2 mole percent adipic acid, reported to have a melting point of 111° C. (Example 4).
Sulfonated aliphatic-aromatic polyesters include polyesters derived from a mixture of aliphatic dicarboxylic acids and aromatic dicarboxylic acids and, in addition, incorporate a sulfonated monomer, such as the salts of 5-sulfoisophthalic acid. U.S. Pat. No. 3,563,942 to Heilberger teaches aqueous dispersions of solvent soluble linear sulfonated aliphatic-aromatic copolyesters which incorporate from 0.1 to 10 mole percent of the sulfonated aromatic monomer. U.S. Pat. No. 3,634,541 to Popp et al. discloses fiber-forming sulfonated aliphatic-aromatic copolyesters which include 0.1 to 10 mole percent of xylylene sulfonated salt monomers. U.S. Pat. No. 3,779,993 to Kibler et al. teaches linear, water-dissipatable sulfonated aliphatic-aromatic copolyesters which incorporate 2 to 12.5 mole percent of a sulfomonomer.
U.S. Pat. No. 4,104,262 to Schade teaches low molecular weight, water dispersible polyesters which incorporate 1-5 mole percent of an alkali metal-sulfo group. U.S. Pat. No. 4,340,519 to Kotera et al. discloses crystalline and non-crystalline sulfonated aliphatic-aromatic copolyesters which incorporate 0.5 to 10 mole percent of an aromatic dicarboxylic acid having a metal sulfonate group. U.S. Pat. No. 4,390,687 to Tung teaches elastomeric aliphatic-aromatic copolyester compositions which incorporate 0.1-5.0 mole percent of an ionic metal sulfonate compound. U.S. Pat. Nos. 4,476,189, 4,525,419, and 4,585,687 to Posey et al. disclose water dispersible aliphatic-aromatic copolyesters which incorporate 6-15 mole percent of at least one sulfomonomer containing an alkali metal sulfonate group.
U.S. Pat. No. 5,171,308 to Gallagher et al. discloses compostable aliphatic-aromatic copolyesters consisting of 5 to 40 mole percent of a C2 to C12 aliphatic diacid, with at least 85 mole percent of the remaining acid component being terephthalic acid, and 1 to 30 mole percent of di(ethylene glycol) and tri(ethylene glycol), with the remainder of the glycol component being chosen from the group consisting of ethylene glycol, 1,3-propanediol, and 1,4-butanediol, along with 0.1 to 2.5 mole percent of the polyester being composed of moieties comprising alkali or alkaline metal sulfo groups. U.S. Pat. No. 5,171,309 to Gallagher et al. teaches biodegradable sulfonated aliphatic-aromatic copolyesters which incorporate 10-40 mole percent hexahydroterephthalic acid along with 0.1 to 2.5 mole percent of moieties comprising alkali or alkaline metal sulfo groups. U.S. Pat. No. 5,219,646 to Gallagher et al. discloses compostable products of blends of starch with certain aliphatic aromatic polyesters which comprise up to 20 mole percent di(ethylene glycol), 0.1 to 15 mole percent alkali metal or alkaline earth metal sulfo groups, 10 to 40 mole percent aliphatic diacids, such as adipic or glutaric acid, ethylene glycol, and 45 to 89.9 mole percent terephthalic acid. Further, U.S. Pat. No. 5,295,985 to Romesser et al. teaches copolyesters of the above mentioned sulfonated aliphatic-aromatic copolyester composition which incorporate 0.1 to 2.5 mole percent of an alkali metal or alkaline earth metal salt of a 4-sulfophthalic radical with additionally 0 to 0.4 mole fraction of a polyester derived from hydroxy acids. U.S. Pat. Nos. 6,018,004 and 6,297,347 to Warzelhan et al. disclose certain biodegradable aliphatic-aromatic copolyesters which may contain 0 to 5 mole percent of a sulfonate compound.
Sulfonated polyetheresters include polyester compositions which include both poly(alkylene ether) glycols, such as poly(ethylene glycol), poly(trimethylene glycol), poly(tetramethylene glycol), and the like, and, in addition, sulfonated monomers, such as the salts of 5-sulfoisophthalic acid. Sulfonated polyetherester compositions have been taught within the art. See, for example, U.S. Pat. Nos. 3,959,213, 4,022,740, 4,119,680, 4,217,441, 5,053,482, 5,097,004, 5,097,005, 5,354,616, 4,006,123, 4,604,446, 5,288,781, 5,290,631, and 5,849,822.
Sulfonated aliphatic-aromatic polyetheresters include polyester compositions which include poly(alkylene ether) glycols, sulfonated monomers, and a mixture of aliphatic dicarboxylic acids and aromatic dicarboxylic acids. Sulfonated aliphatic-aromatic polyetherester compositions have been generally taught within the art. See, for example, U.S. Pat. Nos. 3,779,993, 4,251,652, 4,295,652, 4,315,882, 4,483,976, 4,600,743, 5,070,178, 5,171,308, 5,171,309, 5,219,646, 5,295,985, 5,407,981, 5,593,778, 5,709,940, 6,162,890, and 6,242,560.
U.S. Pat. No. 4,340,519 to Kotera et al. exemplifies sulfonated aliphatic aromatic polyetherester compositions which consist of 25 mole percent ethylene glycol, 70 mole percent 1,4-butanediol, 5 mole percent polytetramethylene glycol (MW=1000), 65 mole percent terephthalic acid, 28 mole percent adipic acid, and 7 mole percent 5-sodium sulfoisophthalic acid. (See, Table 2, Entry A-3.) Said resin was reported to have a melting point of 110° C.
U.S. Pat. No. 4,390,687 to Tung exemplifies sulfonated aliphatic aromatic polyetherester compositions which consist of: (i) 88.7 mole percent 1,4-butanediol, 11.3 mole percent of poly(tetramethylene oxide)glycol having an average molecular weight of 1000, 84.8 mole percent terephthalic acid, 13.2 mole percent dimer acid, and 2 mole percent dimethyl sodium sulfoisophthalate (Example 1); (ii) 88.7 mole percent 1,4-butanediol, 11.3 mole percent of poly(tetramethylene oxide)glycol having an average molecular weight of 1000, 85.8 mole percent terephthalic acid, 13.2 mole percent dimer acid (i.e., dimerized unsaturated fatty acids), and 1 mole percent dimethyl sodium sulfoisophthalate (Example 2); (iii) 90.1 mole percent 1,4-butanediol, 9.9 mole percent of poly(tetramethylene oxide)glycol having an average molecular weight of 1000, 94.4 mole percent terephthalic acid, 4.6 mole percent dimer acid, and 1 mole percent dimethyl sodium sulfoisophthalate (Example 5); (iv) 90.1 mole percent 1,4-butanediol, 9.9 mole percent of poly(tetramethylene oxide)glycol having an average molecular weight of 1000, 93.4 mole percent terephthalic acid, 4.6 mole percent dimer acid, and 2 mole percent dimethyl sodium sulfoisophthalate (Example 6); and (v) 98 mole percent 1,4-butanediol, 2 mole percent of poly(tetramethylene oxide)glycol having an average molecular weight of 1000, 98.5 mole percent terephthalic acid, 0.5 mole percent dimer acid, and 1 mole percent dimethyl sodium sulfoisophthalate (Example 8).
U.S. Pat. No. 4,598,142 to Hilbert et al. exemplifies sulfonated aliphatic aromatic polyetheresters which contain, for example, 59.2 mole percent 1,4-butanediol, 40.8 mole percent diethylene glycol, 65 mole percent terephthalic acid, 5 mole percent sodium 5-sulfoisophthalic acid, and 30 mole percent glutaric acid (Example 1), which was reported to have a crystalline melting point of 92° C.
U.S. Pat. No. 5,171,308 to Gallagher et al. exemplifies sulfonated aliphatic aromatic polyetheresters which contain: (i) 86 mole percent ethylene glycol, 7 mole percent diethylene glycol, 7 mole percent polyethylene glycol, 81 mole percent terephthalic acid, 17 mole percent glutaric acid, and 2 mole percent sodium 5-sulfoisophthalic acid (Entry B1, Table 1B); (ii) 88 mole percent ethylene glycol, 6 mole percent diethylene glycol, 6 mole percent polyethylene glycol, 86 mole percent terephthalic acid, 12 mole percent glutaric acid, and 2 mole percent sodium 5-sulfoisophthalic acid (Entry B2, Table 1B); and (iii) 90 mole percent ethylene glycol, 5 mole percent diethylene glycol, 5 mole percent polyethylene glycol, 88 mole percent terephthalic acid, 10 mole percent glutaric acid, and 2 mole percent sodium 5-sulfoisophthalic acid (Entry B3, Table 1B).
U.S. Pat. No. 5,369,210 to George et al. exemplifies sulfonated aliphatic-aromatic polyetheresters compositions which contain, for example, 95 mole percent ethylene glycol, 5 mole percent diethylene glycol, 69 mole percent 2,6-naphthalenedicarboxylic acid, 18 mole percent sodium 5-sulfoisophthalic acid, and 13 mole percent sebacic acid (Example 6).
U.S. Pat. Nos. 6,258,924 and 6,297,347 to Warzelhan et al. exemplify sulfonated aliphatic-aromatic polyetherester compositions which contain: (i) 80 mole percent 1,4-butanediol, 20 mole percent polyethylene glycol with an average molecular weight of 1500, 68.7 mole percent terephthalic acid, 29.4 mole percent adipic acid, 1.7 mole percent of sodium 5-sulfoisophthalic acid, and 0.2 mole percent of pyromellitic dianhydride, reported to have a melting point of 107.8° C. (Example 3); and (ii) 54.6 mole percent 1,4-butanediol, 46.4 mole percent diethylene glycol, 70.1 mole percent terephthalic acid, 25.3 mole percent adipic acid, and 4.5 mole percent of sodium 5-sulfoisophthalic acid (Example 5).
International Publication WO 01/19909 A1 to Grutke et al. discloses a biodegradable, thermoplastic molding material which includes at least one biodegradable copolyester and 0.01 to 15 weight percent of a hydrophobically modified phyllosilicate.
A shortcoming of the above mentioned materials is that they do not provide a sulfonated aliphatic-aromatic copolyetherester composition with high temperature characteristics, which are required by many substantial enduses, such as film, dual ovenable food trays and the like.